MSRA-0187

A 42-year-old woman with a history of rheumatic heart disease is urgently admitted with a fever, worsening shortness of breath, and a note from her primary care physician confirming the presence of a new heart murmur. During the examination, a harsh pansystolic murmur and early diastolic murmur are detected, and she has a temperature of 38.5 °C with fine basal crepitations in both lungs. Which one of the following should take immediate priority?